Remote control system



June 12, 1945. R. c. BLAKEsLl-:E

REMOTE CONTROL SYSTEM Filed March 4, 1944 S www INVENToRlfaymand'laefle@ [1I/5: ATTORNEY ffm? Patented June 12, 1945 REMOTECONTROL sYsTEM Raymond C. Blakeslee, West Allis, Wis., assignor to TheUnion Switch and Signal Company, Swissvale, Pa., a corporation ofPennsylvania Application March 4, 1944, Serial No. 524,983

Claims.

My invention relates to remote control systems, and more particularly tocentralized trafic control systems for railroads and to the linecircuits' for such systems.

Centralized traffic control systems are now arranged to use the linewires` of existing telephone circuits, a suitable system of this typebeing shown, for example, in Letters Patent of the United States No.2,303,875, issued December 1, 1942, to George W. Baughman and Norman F.Agnew, for Remote `control systems. In some cases the centralizedtraffic control system is superimposed upon a train dispatcherstelephone line equipped with selective calling apparatus for calling theoperators at Ivarious telephone way stations, the` selector systembeingusually of the type disclosed in Letters Patent of the UnitedStates No. 1,343,256, issued June l5, 1920, to J. C. Field.

The centralized traffic control system and the selector system arenon-interfering by reason of the use of dilerent codes, that is, theselecting apparatus of each system is non-responsive to the codestransmitted by the other, but since both systems employ codes of lowfrequency impulses transmitted over the same line-channel through lowpass filters, it is necessary toallot the use of the line to only oneVsystem at a time.

The selector system usually employs manually releasable code Wheelswhich are adapted to transmit their codes immediately when released, ornot at all, while the centralized trafic control system, 'on the otherhand, may be arrangedto store an interrupted code for retransmission inits entirety, as soon as the line is free.

One object of my invention is .to provide improved means forinterlocking two dissimilar code systems, such as those mentioned, insuch a manner that the operator of one system, namely, the call selectorsystem, may gain access to the lineto transmit a code at any timeirrespective of whether or not it is in use atfthe time by the othersystem, the operation of acode wheel being effective to temporarilysuspend Vthe operation of the centralized traffic control system and todisconnect it from the line circuit for the duration of the selectorcode.

A further object of my invention is to provide improved arrangements ofthis character suitable for use when the control oiilce of thecentralized traic control system is at an intermediate point on thedispatchers line, that is to say, at a point remote from the location ofthe selector transmitter.

Itis also the practice to superimpose an additional communicationchannel upon the dispatchers line, employing the two line Wires inparallel as one side of a simplex telegraph or phantom telephonecircuit, or both. As illustrated, for example, in Fig. 1 of theabove-mentioned Patent No. 2,303,875, it has been the practiceheretofore to employ the bridged type of simplex circuit'in which thetelegraph leg is connected to the line wires by a mid point connectionto two relatively high resistances connected across the' line wires inseries. This added resistance is somewhat detrimental tothe operation ofthe telegraph circuit, particularly -when four such connections arerequired, asis the case when the control olceof the centralized trafficcontrol system is at an intermediate point on the line. This difficultyis avoided by a novel arrangement of the apparatus as disclosed herein,which provides `a low resistance path for the telegraph channel throughthe line connections of the centralized traiiiic control and selectorsystems.

One form of apparatus employing myl invention will now be described, andthe novel features thereof willthen be pointed out in claims.

Referring to theaccompanying drawing, the reference characters YI, ZIand Y2, Z2 designate a pair of line Wires which extend from thedispatchers ofce shown at the left, through the territory controlled bythe centralized control system. lThe physical line circuit issectionalized atan intermediate point, at which the C. T. C. ofce islocated, by interposing a telephone transformer or band pass filter 3arrangedto pass currents in the voicefrequency range only.

The line wires provide a voice frequency communication ,channelVextending from a telephone set 5 at the dispatchersoffice over the lineWires YI and ZI to a plurality of jacks l1, such as the one at theselector station shown at the left of ranged to be energized during therotation of any -code wheel, and a pole changer relay JPC controlled bythe code Wheels.4 The periodic operation of relay JPC by any of the codeWheels J supplies impulses of alternately opposite polarity from battery2 with interposed pauses through a low pass filter 4 and an impulsetransformer 6 to the line Wires. The selector impulses normally have afrequency of 3.5 cycles per 5 second, and they serve to operatepolarized selectors 'I2 so as to ring a call bell I6 at the selectedstation..

The territrybontrolledby the C. T. iC. system.- is to be understood tobe that adjacent line Wires 10 Y2 and Z2 only. These line Wires aresupplied n with current from a line battery 80 to proyidea .1. normallyclosed line circuit connecting the'C. T.

C. oice and a plurality of C. T. IG. .staQQIlssuch.. I as the one shownon the drawing'.,.the .C.. .1:5 system corresponding to that l.shownann`..the.. Baughman and Agnew Patent No.. 2,303.31@ here,7 inbeforereferred to, except foc'etain" minor" modifications as described herein.

Fo""an understanding of my invention it is 30 deemed`siif'cieht topli'ritmouttlit the j' codiiifg untsfredure the line'cicuittolbews'teadily energized in"rde' r"'toplfe them m'c'n'di'tion Atoinitiatie "the'transr'issiondf 'a c tdfe, or to'seleci. tively re eiveacode'adtliat the 'stationtrans: A3:5 mitter are"rr'ia'intair'ied'ir'fop'eation bythe` rel sponce oftheasso "ated lin'relay's'to'the code7 elements," becoming disabled if the 'line remain-s1` operrf'r periodrnfal'ferially l'r'iger `'than any elel f ment' 'f` aA code. "The TL,"'office-coding 'nit'is'j' r40 adapted te tiansniit'eentro 'eiiesinvviiiei,trie-,-l line "ci'rciiitnis'periodically 'interrupted by theV'r'ef peated energizatioh of la transmitteday CTZ-'tol Operate the'staiieniine relays R; which are'ef4 high"resistancebiase'd polar'type.The Cf T.' '4i eedesconsist ef cbnii'natibnsjefin'g and short cede'elements' having` abaefrequeneytf endet "L 6 Cycles pqnd...

In drdetdmnimize code distortion wherr the iine wires'are j in "a tatie;a' rsi'stbell u" iseonnectecl arss trie line `ivir'es Y2 ndZ'Zvtprovidef '5 a discharge' patri wneni'remyo'r iiicksp tdisconnectbaltteryfroin'the lirici; M

Each C. T."C.tstatiri1 'adateuto transmit in-- y dicationcodes"by'erierg1aing'-a'-inst relay' M `55 and 'the'nzi periodicallyconnetingfth linev'vi'resf together..-by^"thezrepeated -pe'atieii of'contact zi' of a transmittenrelay the' .esultinglyariation's' in the"linec'urrent causing transformer RT -to Y supply impulses of"alternatelyf'opp'osite .polarity 60 te theP eineeiinexreiay OP., whichisfof 'the sti'e'kc 1' polar type,`so` that relay' OR repeats the codeoperation ofrelay T atthetransrnitting statidni'f "ine,5ni'st..inipu1seof ari' indicatio'rl `'cone op- .I erates the pole chanerrelay'PCattheofce-by 65 means not shown, and relay PC reverses the'polarity o'f4the'currentsuipliedto Vthe line by'bat tery' 80, While frelay Mreverses. the l'connections efor relay R' at .the transmitting station'torendei' Y' it responsive to 'the currentof. reverse polarity. 7l0-This reversal of .the line 4polarity releases lthe'line i relays R attheother` C. Cistatibns, .a't which. the relays Mare deenergizedsothattliesef'stations are held` in an" inactive cnditionur'it'il 'the andthe line circuit is again energized by current of normal polarity.

The telephone transformer 3, which is provided to .isolate the C. T. C.line circuit from the remainder of the dispatchers line, is alsoarranged to block the transmission of selector codes from one section ofthat line to the other, and accordinglyfa selector; code `repeaterprovided to repeat-.,the.selectori-.codes 'delivered to dine., -wires YIand ZI into the circuit comprising the line WiresYZ and Z2, in order tooperate the selectors 'I2 at ;stationsto'the right of the C. T. C. oice.The selector code repeater furthermore comp-ensatesilior theimpairmentof the selector line circuitldueto the, ,connection of the line relays Rin parallel withithe selectors 12 across the line weer; eeaz2..-.

The simplex telegraph channel extends from wire ,XI ethrough transformer6 to the line Wires YI anqnZvI lin paralleLand thence to thev simplex@Oil ii.;f.r0'i1.ik1ent.er.terminal of which it eX-. tendshover oneb oranother of a'plurality of loweresis'tance circuit portions providedinjaccordance with a feature of my invention, to line; wires Y2 andv Z2,thereby by-passing transformer-- 3, and i over thezlinewwireslvY2and Z2in parallelJ to the simplex coil IQ. and thence to Wire X 2.In order "ito provide ra'ci/rcjuit patlrpf uniformly low re-g sistance "for thetelegraphcircigitwunderfall 'con-- ditionsof operation of theC. T. C.and selectorn systems,"V the Vvarious relaycontacts in the -Ci- T. 1f C.line circuit have beenl made of theconti-nuity` transfer type, asshovvn, Vand.' the'centero--terminalof coil v'isI connected-resp'ectivelyftothe-center 'M terminals of resistorL I Il, 'ofbatteryy, and of transformer; I6, the'lastnamedconnection includingv aresistor II-. i The-values pf; resistors l; I0 and II aremade'relativelylow;fandchosenso., as to present substantially thesameresistanceto 1 the telegraph currents iiowing-from coilV 8 tothelineWires Y2 and-Z2, irrespective ofthe-positions of relaysOT-and JBA'P'.jIt vs /ill"be readily apparent that -theLtelegraph-channelfis' notdis'turbed by the operation lof the pole'changer relay f PC, -since-th`ismerely-interchanges wires-[Y2 and-- Z2 ini the `circuit,norWhew-wires jY? and'Z2 arel connectedtogetherduring-ethe'eperation'of a' transmitter at aC. T-. C.station-,-andefurthen thatethe vresistanc-:e of the bypass circuit-'maybe made materially lowerethan' that-of the usual simplex connectioncomprising resistors i bridged r f across thelinewires?thereby'permitting are-- duction inthe voltage-irnpressed-uponthe 'tele-f' graph circuit-andcorrespondingly-decreasing'thefdetrimental effectseof flinefleakagef Consideringnovv the Imode ofoperation-:ofthe I selectorsystemvandnassuming for thee-presentthatlthea T. s'ystemiremains-in: its normal'vvat rest' condition;whenacode Wheel Jeis released. :A1-'1 by the operator-.at thedispatcheris oicefits initial f movement .completes a' circuit' from-one.-t-erminalf B oasuitableilocal source ofcurrentover con-1 tact 96! to:wheel-J endet-hence through .relayexIB to the othenterminalCiof'thesourceythisircuit remaining` closed. until-the Wheel: Jccompletes itsirotationv and .lagainoccupies ,f its. normal positioneas shown. Relay JBtherefore-'picksfurn and :its:y contaotsa and b-.bycconnecting-.battery:to transformer .E `.cause the delivery.of-ia-prelinfiinary=imtransmission of thndicationlcodeis` completedla PR throughiaezloyv'passslienllftoctlansiormern.

from terminal B at the back contact c of relay MP,-through relay JBAP toterminal C so that relayv JBAP picks up to connect transformer I6 to thelinewires Y2 and Z2. This preliminary impulse is not repeated into theline Y2-Z2 because it is delivered to ,transformer I6 before relay J BAPpicks up.

The code wheels J are arranged so that a period of at least one secondelapses after the contact spring 96 makes contact with the code wheel,before it engages the first tooth to complete a circuit over contactspring 9J' to pick up relay JPC. Relay JBA is made sufliciently slowrelease by the connection of a condenser CI Vof large capacity acrossits winding to bridge this interval as well as the intervals between thesuccessive impulses of the code. Relays NR and PR respond to the codeimpulses deliveredto the line wires YI and ZI by` relay JPC, relay NRmaintaining `relays JBA and JBAP picked up until the code wheelcompletes its rotation, and relay PR repeating the operation of relayJPC to deliver the code to the line `wires Y2 and Z2.

During the transmission of the selector code the C. T. C. line battery8U is disconnected by the `opening of back contacts b and d of relayJBAP, and the telegraph channel by-pass from coil 8 to the line wires Y2and Z2 through battery 80 is replaced by the equivalent one from coil8through transformer I6 without interrupting its continuity. Since the C.T."'C. coding units provides a circuit extending over its front con- OTwithout interrupting the continuity of the telegraph channel, and itfollows that the telegraphic transmission over this channel is not in`-terfered with by the C. T. C. transmission.

Relay MP is provided in accordance with a,

modification of the C. T. C. system disclosed in a pending applicationfor Letters' Patent of the United States, Serial No. 496,907, flied July.31, 1943, by Arthur P. Jackel for Remote control systems. In thismodification the control elements of the code are each registered duringthe reception of the next succeeding element without storing them untilthe line is closed at the end of the code, as heretofore. Relay MP isenergized for the duration of the control code and tact c to terminal Bat the reversecontact a of relay OR over which relay JBAP is energizedin response to the energization of relay JBA as in the precedingexamples, provided relay JBA picks up during the transmission of a lineopen code element, that is to say, while relay OR is rerequire the linecircuit to be steadily `energized to condition them to transmit and toreceive codes,\the C. T. C. system becomesdisabled during the intervalbetween the preliminary impulse and the first impulse of the selectorcode,` remaining in that condition until after relay JBAP releases atthe end of the selector code. The station line relaysvR being of thebiased polar type, pick up momentarily in response to alternate impulsesof the selector code, but since they were all released for a relativelylong period when relay JBAP picked up, vand since they do not becomesteadily energized as required to condition the station coding units toreceive code, until yrelay JBAP releases, the C. T.V C. station unitsare nonresponsive to the selector codes, regardless of their codecharacter;

Thefoperation of` contacts c and e of relay JBAP disconnects the ollceline relay OR from the impulse transformer RT and holds it reversed forthe duration of the selector code, thereby holding the C. T. C. ofllcereceiver inactive.

Assuming next thata selector code is initiated while a. C. T. C.indication is being transmitted,

-it will be clear `that the energization of relay JBAP, by holding theC. T. C. line open, will disable the C. T. C. transmitter, interruptingits code before the selector code begins. It will be understood that theC. T. C. station units include stor..

age means such that an interrupted code is retransmitted in its entiretyas soon as the line becomes free so that in this case' the -selectorcode and the C. T. C. code will be transmitted successively. l

Considering next the transmission of a control code by the C. T. C.office coding unit which code, as already mentioned, is generated byopening and closing the line circuit including battery 80 by theperiodic operation of the office transmitter relay OT. Each time relayOT` picks up, the simplex channel by-pass through battery 80 is replacedby one from coil 8 through resistor I0 by the operation of contacts band d of relay versed. On the other hand,if relay JBA picks up duringthe transmission of a long line closed element, the C. T. C. systemretains control of the linelong enough to complete the transmission ofthat element, relay JBAP becoming energized in response to the reversalof relay OR when the element is terminated. In this manner theconversion of a long element into a short one by the action of relayJBAP is prevented, thereby avoiding the improper response to thatelement as received at the field station.l In either case, relay JBAPbecomes energized to free the line prior to the transmission of thefirst impulse It will be evident that in general the operator of theselector system will have no knowledgeof whether or not the line circuitis in use by the C. T. C. system. Such knowledge is unnecessary as he isfree to gain access to the line at any time to interpose selector codeswithout causing any of the C. T. C. codes to fail to be transmitted,land Without causing interference between these codes and the selectorcodes, the onlyeifect being to suspend the operation of the C. T. C.system as long as he continues to use the line. Furthermore, this resultis attained without the provision of any additionalcircuits between thedispatchers oiilce and the C. T. C. ofiice, and without impairing thefull efficiency of utilization of the line wires thereby enabling the C.T. C. system to be superimposed upon a portion of a simplexeddispatchers telephone line without in any manner impairiig its normalmode of operation.

In the foregoing I have assumed that the dis- 6 will replace transformerI6 in the circuits associated with the C. T. C. office coding unit, the

arrangements for providing a low resistance telegraph channel beingequally advantageous under this condition.

Although I have herein shown and described but one form of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of

